1. Field of the Invention
The present invention relates to a power supply apparatus.
Priority is claimed on Japanese Patent Application No. 2010-284907, filed Dec. 21, 2010, the contents of which are incorporated herein by reference.
2. Description of Related Art
Conventionally, as a power supply apparatus that is formed, for example, by connecting a plurality of batteries in parallel, a power supply apparatus is known in which positive main relays are connected in series between an electrical load, which is connected to this power supply apparatus, and the positive polarity terminal of each battery, and negative main relays are connected in series between the electrical load and the negative polarity terminal of each battery, and pre-charge circuits, which are formed by connecting a resistor and a relay in series and which are used for pre-charging, are connected in parallel to each positive main relay (see, for example, Japanese Unexamined Patent Application, First Publication No. 2008-35581 (Patent document 1)).
This power supply apparatus is set such that, in order to prevent an excessively large current flowing to the electrical load, the positive main relays are opened so that the relay of the pre-charge circuit is connected. As a result of this, the current flows to the resistor of the pre-charge circuit.
Moreover, conventionally, as a power storage apparatus that is formed, for example, by connecting a plurality of batteries in parallel, a power storage apparatus is also known in which resistor elements that are used to eliminate any voltage unevenness between the plurality of batteries are connected in series between an electrical load, which is connected to this power storage device, and the positive polarity terminal of each battery, and resistor short-circuiting switches are connected in parallel to each resistor element (see, for example, Japanese Unexamined Patent Application, First Publication No. 2009-212020 (Patent document 2)).
This power storage device is set such that, in order to eliminate voltage unevenness between the plurality of batteries, the resistor short-circuiting switches are turned off, and the plurality of batteries are connected together by the resistor elements. As a result of this, current flows among the plurality of batteries to the resistor elements.
However, in the above-described power supply apparatus according to the conventional technology, as the number of batteries that are connected together in parallel increases, the number of pre-charge circuits also increases. As a consequence, the problems arise that, not only do the costs associated with the apparatus structure increase, but because of the increased size, it is more difficult to install the power supply apparatus.